258 



VERTEBRATA: PISCES OR FISHES. 



FIG. 299. 



Sharks or SQUALI are selachians which are more or less 

 tapering, and which have a most formidable array of teeth; 

 their gill-openings are on the sides of the 

 neck, instead of below, as in the Rays. 

 Sharks vary from three feet to thirty 

 feet in length. 



Of the large sharks it may be said 

 that their great power, formidable teeth, 

 and great ferocity, make them dangerous 

 antagonists. Some kinds, as the White 

 Sharks, have the teeth lancet-shaped, 

 Head of Mackerel an( j seiTa ted on their edges, and they 



Shark. 



can divide a man at a single bite as 

 smoothly as if done by a sweep, of a huge sword. 



FIG. 300. 



Dog-fish, Acanthias americanus, Storer. ' 

 Fio. 301. 



Mackerel Shark, Lamna punctata, Storer. 



The Sharks present considerable diversity of form 

 (Figs. 300-304). The Hammerheads (Fig. 304) have the 

 head shaped like a double-headed hammer. The Spined 



